Rats were trained in a triangular-shaped pool to find a hidden platform, whose location was defined in terms of two sources of information, a landmark outside the pool and a particular corner of the pool. Subsequent test trials without the platform pitted these two sources of information against one another. In Experiment 1 this test revealed a…

We explored whether rhesus monkeys (Macaca mulatta) share one important feature of human essentialist reasoning: the capacity to track category membership across radical featural transformations. Specifically, we examined whether monkeys--like children (Keil, 1989)--expect a transformed object to have the internal properties of its original…

Pigeons learned discrimination rapidly and responded differentially to pictures seen for the first time. The essential feature of a natural discrimination--which is the ability to cope with natural ranges of variation--was approached and earlier experimental results were extended using other classes of stimuli. (Author/RK)